As a reminder of what's coming (pending the final release notes document), here's what you can expect from Groovy 2.1:
complete invoke dynamic support when running with the "indy" JAR on JDK 7
upgrade to GPars 1.0: the Groovy distribution now bundles the GPars 1.0 final release
@DelegatesTo annotation: to help IDEs and the static type checker and compiler to know that method calls in a method parameter closure are delegated to another parameter of the method -- nice for DSLs like in Gradle build files
custom type checking extensions: so you can type check your DSLs at compile-time with your own logic
a meta-annotation system: which allows you to define a new annotation actually combining several others -- which also means being able to apply several AST transformations with a single custom annotation
custom base script class flag for the groovyc compiler: to set a base script class when compiling Groovy scripts
compiler configuration script: to let you define various configuration options for the Groovy compiler, like specifying custom file extensions, various compilation customizers to apply, etc.
compilation customizer builder: a special builder for specifying compilation customizers
jar://, file://, http:// prefix support for launching Groovy scripts from the command line
and many bug fixes and various minor improvements
Thanks a lot to all the contributors to this release!
And on behalf of the team, I wish our Groovy users all the best for 2013!
-- Guillaume Laforge Groovy Project Manager SpringSource, a division of VMware